Low pressure measurement devices in high pressure environments

ABSTRACT

The present invention presents various novel approaches to solving the problems inherent in measuring biological pressures in high pressure systems. Thus, to protect a pressure transducer exposed to fluid flows at higher pressures than its overpressure rating, a novel valve is used that closes a protected leg in which the transducer is located. The various exemplary embodiments of such valves each have a high pressure input, one or more low pressure inputs, and an output. In operation, when a high pressure fluid flow occurs at a high pressure input, such valves automatically close the low pressure inputs. Alternatively, a novel transducer system is presented, which automatically limits the effective pressure sensed by a transducer to a certain maximum.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/575,199, filed on Oct. 7, 2009, which is a continuation applicationof 11/401,695, filed on Apr. 10, 2006, now U.S. Pat. No. 7,617,837,which is a continuation application of 10/316,147, filed on Dec. 9,2002, now U.S. Pat. No. 7,389,788, which claims the benefit of U.S.Provisional Patent Application Ser. Nos. 60/338,859 and 60/338,883, eachfiled on Dec. 7, 2001, all of which are hereby incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to the field of biomedical technology and, inparticular, to methods, systems and apparatus for protecting biologicalpressure measurement devices in high fluid pressure environments.

BACKGROUND OF THE INVENTION

Certain medical procedures, such as, for example, contrast mediainjections during cardiological procedures, can require that liquids(such as radiographic contrast agents in, for example, angiography) beinjected into a patient's system under high pressures. Such pressuresare commonly as high as 1200 lb/in² (psi) or more than 60,000 mm Hg.While performing such procedures it is also desirable to measure thepatient's biological pressures. For example, in angiography it isdesirable to record the much lower intravascular and intracardiacpressures—generally falling within the range of −1 to +6 psi—betweenhigh pressure injections of the contrast media. Generally, pressuretransducers that are designed for physiological measurements cannottolerate even moderate injection pressures and therefore must beisolated from the fluid path during a high-pressure injection. One suchmethod of isolating pressure transducers is described in U.S. Pat. No.5,800,397 (Wilson et al.), that uses a manifold to isolate a lowpressure system line—where a pressure transducer can be located—from ahigh pressure contrast medium injection line based on a spool valveconcept.

Spool-type manifolds are common in industrial applications and canmanage very high pressures. However, such manifolds also require closemanufacturing tolerances, are generally expensive, and are designed foruse in permanent installations. Also, due to its mechanical“stickiness”, the position (open/closed) of a spool-type manifold needsto be monitored by a sensor to avoid malfunction with insipation ofblood during a syringe refill. In medical applications, plastic andelastomeric parts are commonly used. This is because pressures aregenerally low in such environments and sterile parts need to beinexpensive so that for hygienic and safety reasons they can be readilydisposed of after a single use. Such polymers have a drawback; they areless conducive to a consistent fit between different parts, which tendsto decrease reliability. No device currently exists that combines lowcost and ease of manufacture and use with the high pressure capabilityof industrial valves.

In addition, devices adapted to measure high pressures which would, bydefinition, be capable of withstanding those pressures, are simply notsensitive enough to accurately measure physiological pressures. Thus, inthe example discussed above, a physician performing an angiography usingonly a high-pressure sensor could, in fact, monitor the injectionpressure while contrast material is being injected, but would have noway of monitoring the patient's blood pressure when no injection isoccurring. Thus, what is needed in the art is a method of facilitatingthe deployment of pressure measuring devices—that is sensitive enough tomeasure physiological pressures—within high fluid pressure environmentsin a manner that either isolates or protects such devices when highpressures are present.

Thus, within the objects of the present invention are methods, apparatusand systems which facilitate placing devices that make accuratephysiological pressure measurements within environments that areintermittently subjected to high pressure fluid flow.

SUMMARY OF THE INVENTION

The present invention presents various novel approaches to solving theproblems inherent in measuring biological pressures in high pressuresystems. To protect a pressure transducer exposed to fluid flows athigher pressures than its overpressure rating, a novel valve is usedthat closes a protected leg in which the transducer is located. Thevarious exemplary embodiments of such valves each have a high pressureinput, one or more low pressure inputs, and an output. In operation,when a high pressure fluid flow occurs at a high pressure input, thevalve automatically closes the low pressure inputs. Alternatively, anovel transducer system is presented, which automatically limits theeffective pressure sensed by a transducer to a certain maximum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an expanded view of an exemplary valve assembly accordingthe present invention;

FIG. 2 is a cross sectional view taken along a direction normal to fluidflow of the exemplary valve assembly of FIG. 1 depicting the normal (lowpressure) mode of operation;

FIG. 3 is a cross sectional view taken along a direction normal to fluidflow of the exemplary valve assembly of FIG. 1 depicting the open (highpressure) mode of operation;

FIG. 4 is a frontal view of the exemplary valve assembly of FIG. 1;

FIG. 5 is a perspective view of an exemplary valve body according to thepresent invention showing the saline and output ports;

FIG. 6 is a side view of the exemplary valve body of FIG. 5;

FIG. 7 is a cross section taken at the position A-A of the exemplaryvalve body of FIG. 6;

FIG. 8 is a detail drawing of the indicated portion (B) of FIG. 7;

FIGS. 9( a)-(c) illustrate an exemplary disc holder according to thepresent invention;

FIGS. 9( d) and 9(e) illustrate an exemplary valve disc according to thepresent invention;

FIG. 10 depicts an exemplary rotary valve manifold according to thepresent invention in the normal mode;

FIG. 11 depicts the exemplary rotary valve manifold of FIG. 10 in theopen mode;

FIGS. 12( a) and 12(b) depict an alternative exemplary rotary valvemanifold according to the present invention in the normal and openmodes, respectively;

FIG. 13 depicts an exemplary plunger manifold valve according to thepresent invention in the normal mode;

FIG. 14 depicts the exemplary plunger manifold valve of FIG. 12 in theopen mode;

FIGS. 15( a)-15(c) depict open, normal, and assembly views,respectively, of an alternate embodiment of the exemplary disc valve ofFIGS. 1-9 according to the present invention;

FIGS. 16( a)-16(d) depict exemplary relative dimensionalities of a valvebody for the exemplary disc valve of FIG. 15;

FIGS. 17( a)-17(b) depict exemplary relative dimensionalities of a valvedisc for the exemplary disc valve of FIG. 15;

FIGS. 18( a)-18(d) depict exemplary relative dimensionalities of a discholder for the exemplary disc valve of FIG. 15;

FIG. 19 depicts an exemplary 3D rendering of the exemplary disc valve ofFIG. 15;

FIGS. 20( a) and 20(b) depict the normal and open views, respectively ofan exemplary sleeve shuttle valve according to the present invention;

FIGS. 21( a) and 21(b) depict an exemplary bidirectional elastomericvalve according to the present invention;

FIG. 22 depicts an exemplary transducer with barrier apparatus accordingto the present invention;

FIG. 23 depicts a non-disposable portion of the exemplary transducer ofFIG. 22;

FIG. 24 depicts a disposable portion of the exemplary transducer of FIG.22;

FIGS. 25-26 depict an alternative exemplary transducer with barrierapparatus according to the present invention;

FIGS. 27( a)-27(c) depict an exemplary embodiment of an automaticshuttle valve with manual override; and

FIGS. 28( a)-28(c) depict an exemplary disc valve according to thepresent invention with a built-in seat for a low pressure transducer.

DETAILED DESCRIPTION OF THE INVENTION Disc Valve Embodiment

It is within the objects of the present invention to provide a valvethat is inexpensive, reliable, biocompatible, non-allergenic and able towithstand pressures up to 1500 psi. Moreover, the valve must be able towithstand several modes of sterilization (gamma irradiation, ethyleneoxide and e-beam) as well as have a clear housing. It must be easy toremove all bubbles when it is flushed with saline or contrast. Thepressure gradients required in the valve are complex. It must have areliable cracking pressure above 9 psi and, upon opening, ensure that anattached pressure gauge (generally, but not always, located in thesaline port, as described below) is never exposed to pressures aboveapproximately 15 psi (1 atm). To achieve this, because generally apressure sensing connection is very ‘stiff’, parts of the valve must notproject or bulge into the sensing path even at very high pressureconditions. Finally, the components of the valve must not degrade thefidelity of a physiologic pressure signal.

In addition to pressure measurement from a tube system through which ahigh pressure injection is performed, it is often desirable to infusefluids, such as physiological saline, into a patient through the sametubing system through which the high pressure injection is made. Thevalve described herein allows a continuous fluid path to a low pressureinfusion reservoir to tubing connected eventually to the patient's bloodvessel. Injection from another fluid reservoir will passively close offthe low pressure reservoir system, preventing back flow from the highpressure reservoir to the low pressure reservoir.

With reference to FIG. 1, an exemplary embodiment of a high-pressureactivated valve will be described. An exemplary low and high-pressureelastomeric valve is comprised of a disc holder 101, a middle valve disc102 and a valve body 103. The valve body 103 and disc holder 102 aremade of a relatively rigid polymer, such as for example, polycarbonate,and the valve disc 102 is molded of an elastomer, preferably siliconerubber, with a slit in the center.

The elastomeric disc 102 with the slit is sandwiched between the valvebody 103 and disc holder 101 and is affixed at the perimeter of thedisc. Such affixation may be effected by, for example, entrapment,adhesion, mechanical or chemical welding, or any other means known inthe art. The valve body 103 and disc holder 101 are bonded together, by,for example, sonic welding, UV curable adhesive, mechanical threads orsnap (interference) locking, or other bonding or adhesion technologiesas may be known in the art, thus entrapping the disc.

In an exemplary embodiment, the valve has at least two, and preferablythree, ports that communicate with attached tubing. Such ports are, forexample, (a) a contrast inlet port, (b) a saline inlet and pressuretransducer port, and (c) a patient or outlet port. In an exemplaryembodiment the disc holder 101 contains such a contrast inlet port, asis shown in more detail in FIG. 2, described next.

With reference to FIG. 2, a valve body 203 contains a saline/transducer220 and a patient/outlet 221 port. Also, a disc holder inlet port hole222 is tapered outward (in the forward flow direction, i.e., from rightto left in FIG. 2) to create a pocket 240 in front of an elastomericdisc 202 so that as fluid travels through the hole 222 and into theempty pocket, air is forced from the pocket (purged) through the discslit 241 and into the valve body 203 (more precisely, into the cavity inthe valve body which is adapted to fluid flow). Thus, for example, in anangiographic procedure as described above, as contrast media fills theempty pocket 240 of the disc holder 201 and pressure thus builds, theelastomeric valve disc 202 bends and eventually opens the slit 241(which occurs at a certain pressure, known and referred to herein as the‘cracking pressure’) to inject fluid into the valve body. The dimensionsof the pocket allow for control of the cracking pressure; at a givenpressure, exposing a greater surface of the disc to that pressure willincrease the force upon a disc and thus lower the cracking pressure. Thesituation where the slit opens and fluid flows from the inlet port 222through the slit into the valve body 203 is shown in more detail in FIG.3, described below.

Continuing with reference to FIG. 2, in an exemplary embodiment a valvebody 203 has two internal tapers. A narrow taper 205 closest to the disc202 that contains the saline port, and a second wider taper 206. Inoperation, the narrow taper next to the disc 202 allows thesaline/transducer port 220 to be sealed as pressure builds up and beforefluid passes through the disc 202. The second, wider taper 206 andassociated cavity create room for the disc to expand and allow the slit241 to open fully. The converging angles (in the forward flow direction)also promote flushing of air from the valve so that no bubbles are leftbehind.

FIG. 3 depicts the exemplary valve of FIG. 2 in the high pressure fluidflow state described above. With reference to FIG. 3 contrast fluidunder high pressure flows through inlet port 322. This has caused thepressure applied to the right side of the disc 302 to exceed the‘cracking pressure’, which caused disc 302 to expand in the direction offlow (or to the left in FIG. 3), opening the disc slit 341. As the discexpanded it covered the opening of the saline/transducer port 320 in thecavity of the valve body 303. At the same time, the force maintained onthe disc 302 by the incoming fluid keeps the saline port shut duringhigh pressure fluid flow, such as, for example, is experienced in acontrast fluid injection. The first taper has, for example, aring-shaped channel 350 where the saline port 320 is located, thusallowing the interior of the valve body 303 to be completely filled withsaline during initial setup. In an exemplary embodiment, the rest of thevalve body 303 and the corners of the channel are preferably rounded toeliminate any trapping of air bubbles during setup and. Also, such achannel helps air to be removed by a vacuum applied manually using asyringe.

In exemplary embodiments, the valve can be used in connection with lowpressure (60 psi) to high pressure (1200 psi) medical fluid injections.It can also be used with CT, MRI and cardiology contrast media injectionsystems. Additionally, a two-port version of the valve with theelimination of the saline/transducer port 320 can be manufacturedeconomically enough to act as a check valve. Such a high/low pressurevalve is thus inexpensive to manufacture, having a simple design andconsisting of three molded parts that can be assembled and bondedtogether with ease.

The disc holder contains the fluid inlet port and, in exemplaryembodiments, can be molded or machined out of, for example,polycarbonate, PET, acrylic or any other tough polymer as may be knownin the art that can withstand pressures up to 1500 psi. In exemplaryembodiments of the invention the elastomeric disc 202, 302 is preferablycircular and may be, for example, molded or cut from sheet siliconerubber or other elastomers including, for example, polyurethane andlatex. In preferred exemplary embodiments, properties of an elastomericdisc material are, for example, a durometer in the range of 40-70 A,more specifically, for example, 55 A, a tensile strength of 1000-1500psi, an elongation of 300-700%, and a tear strength 150-300 lbs./inch.In a preferred exemplary embodiment the disc may be 0.060″ thick or mayhave a range of 0.020″ to 0.200″ in thickness depending on thedurometer, fluid and slit dimensions. In an exemplary embodiment theslit in the middle of the disc is preferably 0.125″ long, and may be0.050″-0.30″ in length. In preferred exemplary embodiments the disc hasa preferred working surface diameter of 0.580″ and may range from 0.250″to 2.00″.

The valve body 203, 303 is molded or machined out of, for example,polycarbonate, PET, acrylic or other tough polymers that can withstandhigh pressures up to 1500 psi. In exemplary embodiments it contains thefluid outlet port 221, 321 and the saline inlet/transducer port 220,320. In exemplary embodiments the internal shape of the valve body hastwo tapers 205, 206, the first taper being at an angle from the vertical(i.e., from a plane that is normal to the fluid flow direction, andsubstantially parallel to the plane the disc surface is in when the discis non-distended as in FIG. 2) of, for example, 10°-45°, and in apreferred exemplary embodiment 20°, with a width of, for example,0.020″-0.500″, and in a preferred exemplary embodiment 0.115″. Inexemplary embodiments the saline inlet/transducer port 220, 320 islocated in the first taper so that the taper enables the disc 202, 302to close the saline port 220, 320 when fluid flows from the injectionsystem. In exemplary embodiments the second taper may be at an angleupward from the vertical (as above), for example, 45°-90° and preferably0.161″ deep (depth being measured along the direction of fluid flow) tocreate space for the disc to expand and the slit 241, 341 to open forpassage of fluid through the disc.

In exemplary embodiments the valve is assembled by placing a disc 202,302 in the valve body 203, 303. Then the disc holder 201, 301 is placedinto the valve body 203, 303 and the two parts are, for example, pressedtogether mechanically or threaded together and either UV-bonded, sonicwelded or attached by any equivalent means as may be known in the art.The disc is thus trapped between the valve body and the disc holder allalong the disc's outer edge to prevent leaks. In exemplary embodimentsthe three fluid ports may have, for example, male or female luer threadsto conveniently attach to the injection system, patient catheter andsaline/transducer system.

Thus, the disc valve of the current invention accommodates both high andlow pressure fluid systems. Also more than one port can be provided inthe valve body 203, 303, and can thus be closed or opened duringinjection, e.g. up to 4 saline-type ports and can be used for differentpurposes, such as drug injection, patient fluid sampling and a separatepressure transducer. For example, during a high or low pressureinjection (although high enough to exceed the cracking pressure) allsuch ports can be simultaneously closed, and when the injection systemis OFF all such ports will be open, or “ON” and can be usedsimultaneously or as required.

FIG. 4 is a head-on view looking into the contrast fluid output portagainst the direction of fluid flow. With reference to FIG. 4, besidesthe contrast fluid output port 421, there can be seen the channel 450,which is an annular ring whose center is the center of the contrastfluid output port and which is positioned relatively close to the edgeof the valve disc (unseen in FIG. 4). As was described in connectionwith FIG. 3, within the channel 450 is the one or more saline/pressuretransducer ports 420.

FIG. 5 is a perspective view of the valve body (103 with respect toFIG. 1) showing the contrast fluid output port 521, as well as a salineport 520. It is understood that numerous saline ports could be placedanywhere within the channel (450 with respect to FIG. 4; 350 withrespect to FIG. 3) as shall be described below.

FIG. 6 is a side view of the valve body 103 and in the exemplaryembodiment depicted in FIG. 6 are shown some representative exemplarydimensions. The overall diameter of the valve body 601 is shown to beone unit, the diameter of the contrast fluid output port 621 is shown tobe 0.3 units, overall depth 660 (measured herein along the direction offluid flow) is shown to be 0.700 units, and the depth of the non-taperedportion of the valve body 661 as 0.35 units. It is understood that thedimensions in FIG. 6 are merely exemplary, and thus show an example of arelationship between the various dimensions of this apparatus. Numerousother dimensions and relationships therebetween are possible and may infact be desirable, depending on the context and properties of the devicethat are desired to be accentuated or diminished. For example, the depthof the tapered region 662 is one parameter that controls the crackingpressure. The more room there is in a cavity on the side of the valvedisc, the easier it is for the valve disc to be pushed forward (therebeing less resistance provided by air in a cavity than other possiblecomponents), and the lower the cracking pressure. Thus, there is aninverse proportional relationship between the depth 662 and the crackingpressure (“CP”). The greater the area through which a given pressureacts on the disc, the greater the force acting on the disc. ThusCP=k/depth, for some unit determined constant k.

FIG. 7 depicts a cross-section along the line A-A of the exemplary valvebody depicted in FIG. 6. With reference to FIG. 7, a number of exemplarydesign dimensions are displayed, such as the inside diameter of thecontrast medium output port 701; the outside diameter of that outputport 702; the diameter of the cavity at the front edge where the cavityconnects into the contrast fluid output port 703; the diameter at thebeginning of the second tapered region in the valve body cavity 704; thediameter at the beginning of the first tapered region in the valve bodycavity 705; and the inside diameter of the valve body in the non-taperedregion 706, which is the diameter into which a given valve disc willfit. As described above, so as not to have any liquid leakage, thediameter of an exemplary disc designed to fit within the diameter 706will have that same diameter to ensure a tight fit. Exemplary dimensionsof 701-706 are, respectively, 0.149, 0.169, 0.210, 0.350, 0.580 and0.830 units. It is also possible to make the diameter of the discslightly larger in alternative exemplary embodiments, thus ensuring atight fit, where liquids of very low viscosity are used which require agreater attention to leakage prevention.

It is noted that for the exemplary embodiment depicted in FIG. 7, anexemplary valve disc designed to fit therein is depicted in FIG. 9( d)in horizontal top view and in FIG. 9( e) in a vertical side viewshowing. With reference to FIG. 9( d) it can be seen that the diameterof the depicted exemplary valve disc is 0.83 units, identical to thedimension depicted in FIG. 7 element 706. As can be seen with referenceto FIG. 7, there is a region 750 depicted as being surrounded by acircle labeled “B.” This region is depicted in FIG. 8, as shall next bedescribed.

FIG. 8 depicts the detailed B region in a scale magnified by a factor of6 relative to FIG. 7. The area of detail depicted in FIG. 8 is, asshould be obvious to the reader, the exemplary saline port within thevalve body. With reference to FIG. 8, it can be seen that angle 807,representing the angle of the outer taper of the valve body is, in thisexemplary embodiment, 60° off of the vertical and that the distance fromthe corner where the outer tapered region begins in the outer surface ofthe valve body to the center of the saline port is, in this exemplaryembodiment, 0.192 units 801. Also, angle 802, which represents the angleof the inner taper or the first taper 205 (with reference to FIG. 2) isshown to be 30° in this exemplary embodiment. The exemplary diameter ofthe saline port 810 is 0.169 units. As well, with reference to FIG. 8,803 indicates channel depth to manually purge air from the transducerside of the system (which does not require if it is auto purged), 804 awidth of an indent to clamp a valve disc positively, 805 a location ofan indent to clamp a valve disc positively, and 806 a height of anindent for clamping a disc. In this exemplary embodiment, 803-806 are,respectively, 0.025, 0.013, 0.050, and 0.015 units.

With reference to FIGS. 9( a) through 9(c), there are depicted variousviews of the disc holder 101 (with reference to FIG. 1) in the followingexemplary dimensionalities. With reference to FIG. 9( a), an exemplaryoutward diameter 901 is 0.83 units. It is noted that this dimensioncorresponds to element 706 in FIG. 7, which is precisely the exemplarydimension into which the inner diameter of the non-tapered portion ofthe valve body into which the disc holder is to fit. As well, indexnumbers 902-905 represent exemplary inner diameters of the depictedexemplary disc holder, which are 0.810, 0.785, 0.652 and 0.600 units,respectively. With reference to FIG. 9( b), 906 shows an exemplaryheight of a main portion of an exemplary disc holder, 0.300 units, and907 an exemplary height of the high pressure input port, 0.250 units.With reference to FIG. 9( c), 910 shows an exemplary diameter of a mainportion of an exemplary disc holder, 911 an exemplary outer diameter ofthe high pressure input port, 912 an exemplary inner diameter thereof,914 an exemplary port size for creating sufficient pressure, 915 anexemplary pocket size for creating pressure, and 908 an exemplary pocketangle of 82° (from the vertical) for an exemplary pocket, and 913 anexemplary height of a protrusion for clamping within the indent shown inFIG. 8. In this exemplary embodiment, 910-915 are, respectively, 0.810,0.300, 0.169, 0.015, 0.149 and 0.200 units.

With reference to FIGS. 9( d) and 9(e), views of and exemplarydimensions for an exemplary valve disc are shown. With reference to FIG.9( d), as discussed above, an exemplary outer diameter of the valve discis shown as 0.83 units. The exemplary disc slit length 930 is shown as0.15 units. It is noted that given the relationship between the disclength and the diameter of the valve disc, even when the valve disc slitis completely open, there is no concern for leakage at the perimeter ofthe valve disc. Thus, one or more additional saline ports could beplaced anywhere within the annular ring identified as the channel 350with respect to FIG. 3, which would identically and simultaneously beclosed upon the currents of the configuration of the valve depicted inFIG. 3. With respect to FIG. 9( e), 940 the thickness of the valve discis shown and an exemplary thickness of the valve disc shown here in thisexemplary embodiment having 0.06 units of thickness.

The design parameters are used to set a cracking pressure for the valve.In general cracking pressure is a function of disc thickness, slitlength, durometer of the elastomeric disc and the primary taper of thevalve body. Cracking pressure increases with increasing disc thicknessand disc material durometer, and cracking pressure decreases withdecreasing slit length of the disc and primary taper of the valve body.

Rotary Valve Manifold Embodiment

In an alternative exemplary embodiment, a rotary valve apparatus isutilized to switch between the high pressure and low pressureenvironments. FIG. 10 depicts an exemplary rotary valve embodimentaccording to the present invention. With reference to FIG. 10, anexemplary rotary valve is a three-piece design, comprising an outerhousing 1050 and an inner rotating seal 1051. In preferred exemplaryembodiments the three pieces should be molded using, for example,polycarbonate, or as a specific example, Makrolon Rx-2530. In anexemplary embodiment the internal rotating seal is preferably moldedusing TPE. FIG. 10 shows the valve in a static state. There is a pathfrom the saline port 1020 through the center of the TPE seal 1051 to thepatient output port 1021, but there is no open fluid path to the patientoutput port 1021 from the contrast media port 1022.

FIG. 11 depicts the situation where the valve is open for contrastmedia. When contrast media is injected at port 1122, fluid dynamics putsmore pressure on the front of the seal cavity 1151(a), thus rotating thedisc counterclockwise approximately 25 degrees (this angular measurebeing a function of the angular arc that the inner seal must travelbefore a fluid path between contrast and patient is established, itselfa function of the device geometries) before pressure equalizes in thechamber as a result of an open path for the contrast media through thepatient output port 1121. Thus, this rotation of the inner seal closesthe saline fluid path and opens a contrast media to patient fluid path.In addition, the rotation of the inner seal stores energy in the twistor torsion in the member 1160 which protrudes from the inner seal tohold the inner seal 1151 in the housing 1150. Such member is, in thedepicted exemplary embodiment, a 3D rectangular structure whose crosssection is a square whose centroid is the axis of rotation of the innerseal 1151, but such member can be any of a variety of shapes as may beknown in the art. When pressure drops at the contrast media connection,the seal rotates back to the static state, closing the contrast mediaport 1122 and opening the saline path 1120.

FIGS. 12( a) and 12(b) respectively depict an alternative exemplaryembodiment of the rotary valve of FIGS. 10-11. As indicated in FIG. 12(a), this exemplary embodiment utilizes an additional protrusion 1251 ofthe valve housing 1210 into the central rotary seal area creating an airgap 1250 that is compressed when the valve goes into the open state asdepicted in FIG. 12( b), thus storing potential energy in thecompression of the air in the air gap 1250. This air gap assists therotary seal to return to the normal state of FIG. 12( a) when there isno longer any high pressure flow entering the contrast input port 1222and exiting the outlet port 1221, as the compressed air exerts a nettorque (directed into the plane of the drawing) on the rotary seal whichis no longer balanced by any torque resulting from the high pressureflow. In alternative exemplary embodiments, the air gap could bereplaced by a more compressible material relative to the rotary seal, orthe air gap could be contained within the rotary seal without beingexposed to the housing.

Plunger Valve Embodiment

With reference to FIGS. 13 and 14, an alternative exemplary embodimentof the invention is next discussed. These Figures depict the normal andopen states, respectively, of an exemplary plunger valve. This designuses a minimum of parts (three in the depicted exemplary embodiment).With reference to FIG. 13, the normal state is depicted, including thesaline inlet port 1320, contrast inlet port, 1322, and outlet port 1321.The manifold body 1350, 1450 and end cap 1360 can be molded using, forexample, a polycarbonate such as, for example, Makrolon Rx-2530. Theinternal plunger 1351 with diaphragm 1361, 1461 may be molded using, forexample, a 70 durometer EPDM, polyisoprene or equivalent material as maybe known in the art.

FIG. 14 shows the valve in a normal or static state. The path for saline1420 is open and saline flows around the internal plunger 1451 by meansof indentations 1470 caused by a reduced diameter of the plunger 1451 atits central portion. FIG. 14 shows the valve open for contrast media.When the valve sees pressure on the contrast connection 1422 theinternal plunger 1451 is pushed back (rightward in the diagram) towardsthe end cap inside face 1452 and the diaphragm 1461 stretches back(creating potential energy). This closes the saline fluid path 1420 andopens the contrast media to patient fluid path. When pressure drops atthe contrast media connection 1422 the stretched diaphragm 1461 pushesthe plunger 1451 back to the normal state, as depicted in FIG. 13. Thiscloses the contrast media port 1422 and opens the saline path 1420,1421.

Alternate Disc Valve Embodiment

In connection with FIGS. 15 a through 15 c, an alternative embodiment ofthe disc valve will be next described. FIGS. 15( a), 15(b) and 15(c) arealternative exemplary embodiments of the disc valve, and correspondrespectively to FIGS. 3, 2 and 1, showing a variant of the exemplarydisc valve depicted in those Figs. Hence, merely the differences betweenthe exemplary embodiment of FIGS. 1-3 and the exemplary embodiment ofFIGS. 15( a) through 15(c) will be noted. With reference to FIG. 15( a),there is a contrast fluid input port 1522, an output port 1521, and asaline input port 1520. As can be seen with reference to FIG. 15( a),there are the same components in this exemplary embodiment as there werein the exemplary embodiment presented above, i.e., a disc holder, avalve body, and a valve disc. What is notable about the exemplaryembodiment of FIGS. 15( a) through 15(c) is the shape of the cavitywithin the valve body 1503, as well as the differences in the shape ofthe taper where the contrast fluid input port 1522 contacts the valvedisc 1502. A comparison of FIGS. 2 and 3 with FIGS. 15( b) and 15(a),respectively, shows that the cavity within the valve body 1503 in theexemplary embodiment depicted in FIG. 15( a) is significantly largerthan that of FIG. 3. Further, it has more the shape of a rectangle withrounded corners, rather than a trapezoid, such as is created by thefirst and second tapers, with reference to FIGS. 2 and 3. This resultsin a lower cracking pressure, inasmuch as there is less resistance tothe forward movement of the valve disc 1502 than there is in theexemplary embodiment depicted in FIGS. 3 and 2, respectively. Also, onecan see that the saline input port 1520 in FIG. 15 is placed on the top,as opposed to having them placed on the bottom as in FIGS. 2 and 3. Asdescribed above, one or many saline ports can be provided within thechannel and their placement is arbitrary and will, in general, be afunction of the design context.

With reference to FIG. 15( c) and by comparison with FIG. 1, it can beseen that there is some change in the exemplary embodiment depicted inFIG. 15( c) relative to that of FIG. 1 as concerns the valve disc 1502,102. In FIG. 15( c) the valve disc 1502 is not purely flat but has a lipon the rearward or topward in the diagram side. FIGS. 16( a) through16(d), 17(a) through 17(b) and 18(a) through 18(d) provide exemplaryrelative dimensions of various components of the disc valve of FIGS. 15a through 15 c. FIG. 16 collectively provide exemplary relativedimensions for the internal profile of the exemplary valve body.Exemplary dimensions in such exemplary valve body design which areuseful in controlling performance are, for example, inner cavity length0.180 1680, inner cavity height 0.400 1681, output port diameter 0.1491682 and 20° taper 1685. Such parameters are used to achieve desirableshutting of the saline/transducer port and maintain balanced fluiddynamics.

FIG. 17 collectively provide exemplary dimensionalities for the valvedisc according to this alternative exemplary embodiment. It is notedthat FIG. 17( b) depicts a cross-section along the line A-A in FIG. 17(a) across a diameter of the entire disc, and in the depicted orientationthe slit runs vertically and is depicted as 1710 in FIG. 17( b).Further, with reference to FIG. 17( b), one can see the lip structure ofthis exemplary embodiment of the valve disc as discussed above.

The exemplary disc design of FIG. 17( b) having a bulge on one side inthe middle helps in bending the disc to close a saline/transducer portquickly. Also, this exemplary feature increases cracking pressure andprevents the disc from inverting due to any increase in back pressure.In alternative exemplary embodiments the slit in the disc 1710 may havea taper, i.e., be at an angle with the horizontal, which can increasecracking pressure by 25% and also help prevent inversion of the disc dueto any increased back pressure.

Accordingly, the disc holder, as shown in FIG. 18, includes a 21° taperfrom the exemplary dimensions of 0.450 to 0.149 to accommodate the bulgein the disc in order to increase the cracking pressure and preventinversion of the disc.

Finally, FIGS. 18( a) through 18(d) give exemplary relative dimensionsof the disc holder 1501 in FIG. 15( c). As above, these relativedimensions are merely exemplary and numerous other dimensions could beutilized changing some or all of the dimension relationships depicted inFIGS. 16 through 18 collectively, as may be implemented by one skilledin the art.

FIG. 19 is a 3D rendering of the components of the disc valve of FIGS.15 through 18 showing the three components, the valve body 1903, showingthe saline port 1920 provided within it, the valve disc 1902 and thedisc holder 1901.

Spool Valve Embodiment

What will next be described, with reference to FIG. 20, is an exemplaryspool valve embodiment according to the present invention. FIG. 20( a)depicts the valve in the open position and FIG. 20( b) depicts the valvein the closed position. With reference to FIG. 20( a), there is a salineport 2020, a output port that goes to the patient 2021, and a contrastmedium or high pressure input port 2022. There is provided as well aspring 2050 which exerts pressure on a spool 2051, which is a cylinderwith a hollowed-out center which is accessed from the high pressure port2022 via an orifice 2052. When there is no high pressure on the backcircular plane of the spool 2051, the spring 2050 holds it in suchmanner that the saline port 2020 has a fluid pathway to the patientoutput port 2021. This is the situation depicted in FIG. 20( a). Withreference to FIG. 20( b), the situation is depicted where there is highpressure fluid flow entering the valve through the high pressure inputport 2022, which exerts pressure on the back cylindrical plane 2060 ofthe spool and pushes it against the spring 2050 such that it moves tothe left in the diagram or in the direction of fluid flow, occluding theopening of the saline port 2022, thus protecting it. Therefore, if a lowpressure, high-sensitivity transducer can be placed within theprotective saline port 2020 such that it can measure the pressure offluid, and therefore the pressure in the patient when there is no highpressure flow, and when there is high pressure fluid flow at the highpressure input port 2022, the protected leg and therefore the transducerwithin it are cut off from the fluid flow and the high pressure of thehigh pressure fluid flow is not exerted on the low-pressure transducer.

Bi-Directional Disc Valve

With reference to FIGS. 21( a) and 21(b), an additional exemplaryembodiment of the disc valve is depicted. As can be seen from FIG. 21(b), this is a bi-directional high pressure elastomeric valve. Port 12121 and Port 3 2123 could either be used as an input or an output forhigh pressure fluid flow. In the exemplary embodiment depicted in FIG.21( b), the valve disc 2102 is similar to the valve disc used in theprior exemplary unidirectional embodiments discussed, however the shapesof the disc holder 2101 and the valve body 2103 have changed somewhat tobecome more similar. This is because in order for the flow to bebi-directional there needs to be a cavity on both sides of the valvedisc. Thus the two cavities tend to look similar. While saline ports canbe provided on both sides, they can only be protected from high pressureflow when the saline port that is used is on the output side of the highpressure flow. For example, with reference to FIG. 21( b), the depictedsaline Port 2 2120 can only be protected if Port 1 2121 is the input andPort 3 2123 is the output. Although the exemplary embodiment depicted inFIG. 21( b) shows an identical angle of displacement of the valve discunder high pressure flow, i.e., 30° off of the vertical in eachdirection, it is not necessary that these angles be identical, anddesigners will use variations in the sizes of the cavities on eitherside of the valve disc as well as the angle of full distention of thevalve disc to vary the cracking pressure in each of the forward andbackward directions. There are many exemplary uses which such abi-directional high pressure elastomer valve would have, among them, forexample, are using it in the forward direction as the unidirectionalvalve described above, and then also using it as a high pressure checkvalve, such that back flow is allowed at a certain high pressure whichexceeds the cracking pressure in the backward direction.

It is thus understood that the bi-directional high pressure elastomericvalve depicted in FIGS. 21( a) and 21(b) will have many uses beyondsimply protecting low-pressure transducers or low-pressure systems fromhigh pressure flow in angiographic procedures.

Enhanced HP Transducer (No Valve Protection Required)

Within the objects of the present invention are methods and systems toprotect low-pressure systems (such as, for example, those containinglow-pressure and high sensitivity, but low over-pressure ratedtransducers) from high pressure flow. Thus far what has been describedare various exemplary embodiments of the valves which are designed to dothat. The other side of the coin, however, is to design a transducerwith additional apparatus that will protect it from the pressuresexerted by high pressure fluid flow, even if it is exposed to such highpressure fluid flow. What is next described with reference to FIGS. 22through 26 are transducer designs that do just that. Using thetransducers, the exemplary embodiments of which are depicted in FIGS. 22through 26, there is no need to put the transducer in a protectedlow-pressure line, such as, for example, the saline port as describedabove in the valve embodiments. Rather, the transducer can be placedwithin a high pressure line. When high pressure fluid flow is present inthe line the transducer will be exposed to that high pressure, but abarrier apparatus will protect the transducer such that the pressureexerted against it is held at certain maximum which is below theoverpressure rating for the transducer. When there is low pressure inthe line the transducer is free to operate in its full dynamic range andmeasure, according to its high sensitivity, various intercardiac,intravenous, or interstitial pressures as may be desirous to be measuredin a given patient.

With reference to FIG. 22, there is provided a transducer 2201 within atransducer housing 2202 and a transducer contact 2203 which impacts uponthe transducer 2201 pressing against the impact plane 2205 of thetransducer. The transducer contact 2203 is moved ultimately by themembrane contact 2210 which is within a high pressure tubing 2250 andexposed to any high pressure fluid flow, as indicated by the arrow 2290at the bottom right of the tubing. The fluid pressure is exerted on thetransducer contact 2203 via a pressure transmission rod 2204 which isconnected to the plane of a membrane 2220 via a membrane contact 2210.Thus, the pressure transmission rod, the membrane contact, thetransducer contact and the transducer, are all insulated from actualcontact with the fluid for hygienic purposes. The only part havingcontact with the actual fluid is the membrane 2220. The fluid is notallowed to enter into the transducer housing 2202 by operation of theseal ring 2291, which provides a means to insert the transducer housinginto the high pressure tubing but seal it off from any fluidcommunication therewith.

As can be seen with reference to FIG. 22, a fluid flow in the highpressure tubing will exert pressure on the membrane 2220, which willtransmit it to the membrane contact 2210 and by means of a pressuretransmission rod 2204 transfer the resultant force to the transducercontact 2203. The transducer contact 2203 will then be pushed in theupward direction, exerting a pressure on the transducer 2201. However,the transducer contact is limited as to how much pressure it can exertagainst a transducer by means of the transducer contact limiter 2251,which is a ring around the outward perimeter or circumference of thetransducer, which serves to stop the transducer contact from any furtherupward vertical motion. The transducer contact limiter is comprised ofany rigid material as may be known in the art. Although it may not beabsolutely rigid the transducer contact limiter will have a springconstant which is significantly more rigid than that of the transducer.Thus, in relative terms the transducer contact limiter provides muchmore rigid resistance to the upward motion of the transducer contactthan does the transducer itself. This allows the transducer to measureany pressure between zero and a certain maximum which is governed by thestopping effect that the transducer contact limiter has on the upwardmotion of the transducer contact. This maximum pressure which can bemeasured by the transducer will, of course, be set below itsoverpressure rating by a significant safety margin, as may be chosen bya given designer according to criteria as may be known in the art. In anexemplary embodiment such safety margin will be 20%.

Such a configuration allows the transducer to measure a wide range ofpressures in a very sensitive manner within the biological orphysiological regime, such as, for example, pressures normally occurringin patients to which the high pressure tubing is connected; however,when there is high pressure flow within the high pressure tubing 2250,such as in angiographic procedures as described above, the pressurereading by the transducer will be capped at the maximum pressure.

Also shown in FIG. 22 is ECG contact 2280, the functionality of which isexplained in detail below with reference to FIGS. 25 and 26.

FIG. 23 illustrates the portion of the transducer depicted in FIG. 22which does not contact the fluid and is a non-disposable multi-useapparatus.

FIG. 24 depicts the disposable portion of the transducer assemblydepicted in FIG. 22, being the membrane 2420, the seal ring 2491, and astainless steel tube 2492. It is within the hollow of the stainlesssteel tube that the transducer contact and the transmission rod move upor down, as determined by the pressure exerted against the membrane. Ascan be seen in the exemplary embodiment of the membrane depicted in FIG.24, it can withstand pressures up to 1500 psi, which means that it isimpervious to fluid flow up to those pressures.

FIGS. 25 and 26 depict an alternative exemplary embodiment of the highpressure transducer. In this embodiment the transducer probe (being thepressure transmission rod in the membrane contact, as depicted in FIG.22), does not extend downward into the high pressure tubing, but measurepressures at the tubing layer itself. This is done by screwing on thetransducer housing as opposed to inserting it within the cavity of thehigh pressure tubing. The functionality of the alternative exemplaryembodiment is equivalent, the only differences between the two exemplaryembodiments being the mechanism of insertion or affixation of thetransducer, pressure transmission rod, and membrane contact to the highpressure tubing in such manner that it can reliably measure pressures.In the second exemplary embodiment since there is no protrusion into thevolume of the tubing, there is no need for the metallic tube 2492 ofFIG. 24. Thus, the ECG contact needs a conductive pathway to the fluidin the tube. This is provided by the ECG metal lead 2581, to which thecircular ECG Contact 2580 connects.

The ECG contact is utilized in the following manner. During medicalprocedures, catheters are often inserted into the vasculature to measurepressure, withdraw blood or inject contrast media or other substances.In such instances the lumen of the catheter tubing is generally filledwith a conductive liquid, such as, for example, saline, blood orradiographic contrast media.

During certain medical procedures such as, for example, angiography, itis also often desirable to obtain an electrocardiographic measurement ofthe heart's electrical activity. Such a measurement is usually obtained,for example, from electrodes applied to the patient's skin or fromelectrodes mounted on the outside of catheters. A minimum of twoelectrocardiographic electrode attachments to the patient are generallyrequired and the voltage potential between the electrodes (either singlyor in groups) is recorded over time. These measurements allow monitoringof the patient's condition as well as diagnosis of specific heartabnormalities, such as, for example, such as lack of blood flow.

In the exemplary embodiment depicted in FIGS. 25 and 26, theelectrocardiographic (ECG) electrodes from the heart can be obtainedthrough the conductive fluid in the lumen of the catheter in thepatient. The other (return path) electrode, or combination ofelectrodes, can be obtained from surface electrodes attached to thepatient's skin or from electrodes attached to the side of the catheterwithin the patient. Alternatively, two electrode leads could be obtainedfrom the lumens of a catheter with two or more lumens filled with aconductive substance.

The sensing of at least one ECG electrode from the catheter lumen wouldallow easier ECG measurements for patients undergoing such medicalprocedures because it would simplify or eliminate the need for skinelectrodes. It would also allow a recording of the intravascular ECG,which may have diagnostic importance or be useful for other purposes asmay be known in the art.

Shuttle Valve with Manual Override

FIG. 27( a) through 27(c) depict an exemplary embodiment of a shuttlevalve with manual override. In general, in the exemplary embodiments ofvalves discussed so far, there have been two position/three way valves,which direct either saline or contrast to a single port connected to thepatient. In such systems, it is further required to have a threeposition/three way stopcock distal from the valve to aspirate fluid fromand administer fluid to the same patient connection. This increases costand complexity. The exemplary embodiment shuttle valve depicted in FIG.27 merges these two functions in one valve by adding an additionalsample/aspiration port 2723, as shall next be described. The exemplaryembodiment of FIG. 27 also allows existing two position/three way valvesto be located at the extreme distal end of a disposable set, which mayin fact increase the accuracy and fidelity of biological pressurewaveforms by substituting a lumen filled with contrast with one filledwith less viscous saline. Moreover, a push-button style valve isgenerally easier to actuate than a similar rotary style valve.

In an exemplary embodiment of the shuttle valve shown in FIG. 27, theports are configured in parallel. This facilitates the use of aside-by-side dual lumen tube. With reference to FIG. 27( a), there isdepicted the normal state of the valve where the saline port 2720 has anopen fluid communication pathway with the patient output port 2721. Thisfigure also depicts the contrast port 2722 as described above, and anadditional port unique to this embodiment which is the sample/aspirationport 2723. With reference to FIG. 27( b), the shuttle has movedrightward within the figure, according to the following process. Thespring on the left, shown with the larger windings, 2750 has a higherspring constant. The spring on the right 2751 has a lower springconstant. In normal operation as depicted in FIG. 27( a), the springwith lower force constant biases the shuttle 2750 against the springwith the higher force constant. During an injection, however, fluidpressure from the flow into the contrast port 2722 shifts the shuttleagainst the spring with the lower force constant 2751 closing up thesaline port 2720 to the patient port 2721 and opening the contrast port2722 to the patient port 2721. Once the injection is complete, the lowforce constant spring 2751 once again biases the shuttle toward the highforce constant spring 2750, thus reopening the connection between thepatient 2721 and saline 2720 ports while closing the connection betweenthe contrast 2722 and patient 2721 ports.

Additionally, according to the exemplary embodiment depicted in FIG. 27(a), when desired the shuttle may be manually biased further towards thehigh force constant spring 2750 which opens a connection between thesample aspiration port 2723 and the patient port 2721 by means of abypass connection 2760 from bypass inlet 2761 to bypass outlet 2762between the patient 2721 and sample 2723 ports. This situation isdepicted in FIG. 27( c). This opening of a connection between thesample/aspiration 2723 and patient 2721 ports closes the other twoports, namely the contrast port 2722 and the saline port 2720. Such aconfiguration allows for a sample aspiration, blood aspiration, or theadministration of medications. The manual biasing of spring 2750 can beimplemented and released via a push button, or such other device as maybe known in the art.

FIGS. 28( a) through 29(c) depict an alternate exemplary embodiment of adisc valve. In this exemplary embodiment, location for a transducer isprovided within the valve body itself. With reference to FIG. 28( a),there is provided an output port 2821, a saline port 2820, and atransducer lead port 2890, through which electric leads running out of atransducer can be run. FIG. 28( b) depicts a cross section of FIG. 28(a), depicting a high pressure input 2822, an output port 2821, a salineport 2820, and an exemplary location for a transducer 2891. Both thesaline port and the transducer at location 2891 are sealed off from anyhigh pressure flow by disc member 2802, here shown in the normalposition. FIG. 28( c) depicts the disc in the open position, as whenhigh pressure flow enters via high pressure input port 2822.

The present invention has been described in connection with exemplaryembodiments and exemplary preferred embodiments and implementations, asexamples only. It will be understood by those having ordinary skill inthe pertinent art that modifications to any of the embodiments orpreferred embodiments may be easily made without materially departingfrom the scope and spirit of the present invention as defined by theappended claims.

1. A method comprising: providing, by a fluid injection system, a fluidvalve comprising a first inlet port, a second inlet port, an outletport, and a valve body comprising an elastomeric component, wherein theoutlet port is substantially aligned with the first inlet port, whereinthe valve body defines a first fluid path from the first inlet port tothe outlet port, and wherein the valve body further defines a secondfluid path from the second inlet port to the outlet port; allowing, bythe elastomeric component, the second fluid path to be open when thereis substantially no fluid flow through the valve body; and closing thesecond fluid path, by the elastomeric component, when a fluid pressureat the first inlet port exceeds a defined pressure.
 2. The method ofclaim 1, further comprising: providing, by the fluid injection system,first tubing from the first inlet port of the fluid valve to a firstfluid reservoir; and providing, by the fluid injection system, secondtubing from the second inlet port of the fluid valve to a second fluidreservoir.
 3. The method of claim 2, wherein the first fluid reservoircontains contrast media, and wherein the second fluid reservoir containssaline.
 4. The method of claim 1, wherein allowing the second fluid pathto be open comprises allowing, by the elastomeric component, the secondfluid path to be open when the fluid pressure at the first inlet port isless than the defined pressure.
 5. The method of claim 1, wherein whenthe fluid pressure at the first inlet port exceeds the defined pressure,the second fluid path is closed due to movement of the elastomericcomponent.
 6. The method of claim 1, wherein when the fluid pressure atthe first inlet port exceeds the defined pressure, the second fluid pathis closed due to a change in shape of the elastomeric component.
 7. Themethod of claim 6, wherein the first fluid path is open when the fluidpressure at the first inlet port exceeds the defined pressure.
 8. Themethod of claim 1, wherein the first inlet port of the fluid valve isaligned on a first axis, and wherein the second inlet port of the fluidvalve is aligned on a second axis, the second axis being substantiallydifferent than the first axis.
 9. The method of claim 1, wherein thefirst fluid path comprises a unidirectional fluid path from the firstinlet port to the outlet port.
 10. A method comprising: providing, by afluid injection system, a fluid valve comprising a first inlet portaligned on a first axis, a second inlet port aligned on a second axissubstantially different than the first axis, an outlet port, and a valvebody comprising an elastomeric component, wherein the valve body definesa first fluid path from the first inlet port to the outlet port, andwherein the valve body further defines a second fluid path from thesecond inlet port to the outlet port; allowing, by the elastomericcomponent, the second fluid path to be open when there is substantiallyno fluid flow through the valve body; and closing the second fluid path,by the elastomeric component, when a fluid pressure at the first inletport exceeds a defined pressure.
 11. The method of claim 10, furthercomprising: providing, by the fluid injection system, first tubing fromthe first inlet port of the fluid valve to a first fluid reservoir; andproviding, by the fluid injection system, second tubing from the secondinlet port of the fluid valve to a second fluid reservoir.
 12. Themethod of claim 10, wherein allowing the second fluid path to be opencomprises allowing, by the elastomeric component, the second fluid pathto be open when the fluid pressure at the first inlet port is less thanthe defined pressure.
 13. The method of claim 10, wherein when the fluidpressure at the first inlet port exceeds the defined pressure, thesecond fluid path is closed due to movement of the elastomericcomponent.
 14. The method of claim 10, wherein when the fluid pressureat the first inlet port exceeds the defined pressure, the second fluidpath is closed due to a change in shape of the elastomeric component.15. The method of claim 14, wherein the first fluid path is open whenthe fluid pressure at the first inlet port exceeds the defined pressure.16. The method of claim 10, wherein the first fluid path comprises aunidirectional fluid path from the first inlet port to the outlet port.17. The method of claim 10, wherein the second inlet port is located ina taper at an angle from a plane that is normal to a direction of fluidflow from the first inlet port.
 18. A fluid valve comprising: a firstinlet port; a second inlet port; an outlet port substantially alignedwith the first inlet port; a valve body defining a first fluid path fromthe first inlet port to the outlet port, the valve body further defininga second fluid path from the second inlet port to the outlet port; meansfor allowing the second fluid path to be open when there issubstantially no fluid flow through the valve body; and means forclosing the second fluid path when a fluid pressure at the first inletport exceeds a defined pressure.
 19. The fluid valve of claim 18,wherein the first fluid path is open when the fluid pressure at thefirst inlet port exceeds the defined pressure.
 20. The fluid valve ofclaim 18, wherein the first inlet port of the fluid valve is aligned ona first axis, and wherein the second inlet port of the fluid valve isaligned on a second axis, the second axis being substantially differentthan the first axis.
 21. A fluid valve comprising: a first inlet portaligned on a first axis; a second inlet port aligned on a second axis,the second axis being substantially different than the first axis; anoutlet port; a valve body defining a first fluid path from the firstinlet port to the outlet port, the valve body further defining a secondfluid path from the second inlet port to the outlet port; means forallowing the second fluid path to be open when there is substantially nofluid flow through the valve body; and means for closing the secondfluid path when a fluid pressure at the first inlet port exceeds adefined pressure.
 22. The fluid valve of claim 21, wherein the firstfluid path is open when the fluid pressure at the first inlet portexceeds the defined pressure.
 23. The fluid valve of claim 21, whereinthe second inlet port is located in a taper at an angle from a planethat is normal to a direction of fluid flow from the first inlet port.